/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.sanselan.formats.tiff.datareaders;

import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;

import org.apache.sanselan.ImageReadException;
import org.apache.sanselan.common.BinaryConstants;
import org.apache.sanselan.common.BitInputStream;
import org.apache.sanselan.common.PackBits;
import org.apache.sanselan.common.mylzw.MyLZWDecompressor;
import org.apache.sanselan.formats.tiff.constants.TiffConstants;
import org.apache.sanselan.formats.tiff.photometricinterpreters.PhotometricInterpreter;

public abstract class DataReader implements TiffConstants, BinaryConstants
{
	protected final PhotometricInterpreter photometricInterpreter;
	protected final int bitsPerSample[];
	protected final int last[];

	protected final int predictor;
	protected final int samplesPerPixel;

	public DataReader(PhotometricInterpreter photometricInterpreter,
			int bitsPerSample[], int predictor, int samplesPerPixel)
	{
		this.photometricInterpreter = photometricInterpreter;
		this.bitsPerSample = bitsPerSample;
		this.samplesPerPixel = samplesPerPixel;
		this.predictor = predictor;
		last = new int[samplesPerPixel];
	}

	//	public abstract void readImageData(BufferedImage bi, ByteSource byteSource)
	public abstract void readImageData(BufferedImage bi)
			throws ImageReadException, IOException;

	protected int[] getSamplesAsBytes(BitInputStream bis)
			throws ImageReadException, IOException
	{
		int result[] = new int[bitsPerSample.length];
		for (int i = 0; i < bitsPerSample.length; i++)
		{
			int bits = bitsPerSample[i];
			int sample = bis.readBits(bits);
			if (bits < 8)
			{
				int sign = sample & 1;
				sample = sample << (8 - bits); // scale to byte.
				if (sign > 0)
					sample = sample | ((1 << (8 - bits)) - 1); // extend to byte
			}
			else if (bits > 8)
			{
				sample = sample >> (bits - 8); // extend to byte.
			}
			result[i] = sample;
		}

		return result;
	}

	protected int[] applyPredictor(int samples[], int x)
	{
		if (predictor == 2) // Horizontal differencing.
		{
			for (int i = 0; i < samples.length; i++)
			{
				if (x > 0)
				{
					samples[i] = 0xff & (samples[i] + last[i]);
				}
				last[i] = samples[i];
			}
		}

		return samples;
	}

	private int count = 0;

	protected byte[] decompress(byte compressed[], int compression,
			int expected_size) throws ImageReadException, IOException
	{
		switch (compression)
		{
			case 1 : // None;
				return compressed;
			case 2 : // CCITT Group 3 1-Dimensional Modified Huffman run-length encoding.
				throw new ImageReadException("Tiff: unknown compression: "
						+ compression);
			case TIFF_COMPRESSION_LZW : // LZW
			{
				InputStream is = new ByteArrayInputStream(compressed);

				int LZWMinimumCodeSize = 8;

				MyLZWDecompressor myLzwDecompressor = new MyLZWDecompressor(
						LZWMinimumCodeSize, BYTE_ORDER_NETWORK);

				myLzwDecompressor.setTiffLZWMode();

				byte[] result = myLzwDecompressor.decompress(is, expected_size);

				return result;
			}

			case TIFF_COMPRESSION_PACKBITS : // Packbits
			{
				byte unpacked[] = new PackBits().decompress(compressed,
						expected_size);
				count++;

				return unpacked;
			}

			default :
				throw new ImageReadException("Tiff: unknown compression: "
						+ compression);
		}
	}

}